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<html lang="en">
	<head>
		<title>three.js webgl - lines - colors</title>
		<meta charset="utf-8">
		<meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
		<link type="text/css" rel="stylesheet" href="main.css">
	</head>
	<body>

		<div id="info">
			<a href="https://threejs.org" target="_blank" rel="noopener">three.js</a> - color lines<br/>
			<a href="http://en.wikipedia.org/wiki/Hilbert_curve">Hilbert curve</a> thanks to <a href="https://openprocessing.org/user/5654">Thomas Diewald</a>
		</div>

		<script type="importmap">
			{
				"imports": {
					"three": "../build/three.module.js",
					"three/addons/": "./jsm/"
				}
			}
		</script>

		<script type="module">

			import * as THREE from 'three';

			import * as GeometryUtils from 'three/addons/utils/GeometryUtils.js';

			let mouseX = 0, mouseY = 0;

			let windowHalfX = window.innerWidth / 2;
			let windowHalfY = window.innerHeight / 2;

			let camera, scene, renderer;

			init();

			function init() {

				camera = new THREE.PerspectiveCamera( 33, window.innerWidth / window.innerHeight, 1, 10000 );
				camera.position.z = 1000;

				scene = new THREE.Scene();

				renderer = new THREE.WebGLRenderer( { antialias: true } );
				renderer.setPixelRatio( window.devicePixelRatio );
				renderer.setSize( window.innerWidth, window.innerHeight );
				renderer.setAnimationLoop( animate );
				document.body.appendChild( renderer.domElement );

				//

				const hilbertPoints = GeometryUtils.hilbert3D( new THREE.Vector3( 0, 0, 0 ), 200.0, 1, 0, 1, 2, 3, 4, 5, 6, 7 );

				const geometry1 = new THREE.BufferGeometry();
				const geometry2 = new THREE.BufferGeometry();
				const geometry3 = new THREE.BufferGeometry();

				const subdivisions = 6;

				let vertices = [];
				let colors1 = [];
				let colors2 = [];
				let colors3 = [];

				const point = new THREE.Vector3();
				const color = new THREE.Color();

				const spline = new THREE.CatmullRomCurve3( hilbertPoints );

				for ( let i = 0; i < hilbertPoints.length * subdivisions; i ++ ) {

					const t = i / ( hilbertPoints.length * subdivisions );
					spline.getPoint( t, point );

					vertices.push( point.x, point.y, point.z );

					color.setHSL( 0.6, 1.0, Math.max( 0, - point.x / 200 ) + 0.5, THREE.SRGBColorSpace );
					colors1.push( color.r, color.g, color.b );

					color.setHSL( 0.9, 1.0, Math.max( 0, - point.y / 200 ) + 0.5, THREE.SRGBColorSpace );
					colors2.push( color.r, color.g, color.b );

					color.setHSL( i / ( hilbertPoints.length * subdivisions ), 1.0, 0.5, THREE.SRGBColorSpace );
					colors3.push( color.r, color.g, color.b );

				}

				geometry1.setAttribute( 'position', new THREE.Float32BufferAttribute( vertices, 3 ) );
				geometry2.setAttribute( 'position', new THREE.Float32BufferAttribute( vertices, 3 ) );
				geometry3.setAttribute( 'position', new THREE.Float32BufferAttribute( vertices, 3 ) );

				geometry1.setAttribute( 'color', new THREE.Float32BufferAttribute( colors1, 3 ) );
				geometry2.setAttribute( 'color', new THREE.Float32BufferAttribute( colors2, 3 ) );
				geometry3.setAttribute( 'color', new THREE.Float32BufferAttribute( colors3, 3 ) );

				//

				const geometry4 = new THREE.BufferGeometry();
				const geometry5 = new THREE.BufferGeometry();
				const geometry6 = new THREE.BufferGeometry();

				vertices = [];
				colors1 = [];
				colors2 = [];
				colors3 = [];

				for ( let i = 0; i < hilbertPoints.length; i ++ ) {

					const point = hilbertPoints[ i ];

					vertices.push( point.x, point.y, point.z );

					color.setHSL( 0.6, 1.0, Math.max( 0, ( 200 - hilbertPoints[ i ].x ) / 400 ) * 0.5 + 0.5, THREE.SRGBColorSpace );
					colors1.push( color.r, color.g, color.b );

					color.setHSL( 0.3, 1.0, Math.max( 0, ( 200 + hilbertPoints[ i ].x ) / 400 ) * 0.5, THREE.SRGBColorSpace );
					colors2.push( color.r, color.g, color.b );

					color.setHSL( i / hilbertPoints.length, 1.0, 0.5, THREE.SRGBColorSpace );
					colors3.push( color.r, color.g, color.b );

				}

				geometry4.setAttribute( 'position', new THREE.Float32BufferAttribute( vertices, 3 ) );
				geometry5.setAttribute( 'position', new THREE.Float32BufferAttribute( vertices, 3 ) );
				geometry6.setAttribute( 'position', new THREE.Float32BufferAttribute( vertices, 3 ) );

				geometry4.setAttribute( 'color', new THREE.Float32BufferAttribute( colors1, 3 ) );
				geometry5.setAttribute( 'color', new THREE.Float32BufferAttribute( colors2, 3 ) );
				geometry6.setAttribute( 'color', new THREE.Float32BufferAttribute( colors3, 3 ) );

				// Create lines and add to scene

				const material = new THREE.LineBasicMaterial( { color: 0xffffff, vertexColors: true } );

				let line, p;
				const scale = 0.3, d = 225;

				const parameters = [
					[ material, scale * 1.5, [ - d, - d / 2, 0 ], geometry1 ],
					[ material, scale * 1.5, [ 0, - d / 2, 0 ], geometry2 ],
					[ material, scale * 1.5, [ d, - d / 2, 0 ], geometry3 ],

					[ material, scale * 1.5, [ - d, d / 2, 0 ], geometry4 ],
					[ material, scale * 1.5, [ 0, d / 2, 0 ], geometry5 ],
					[ material, scale * 1.5, [ d, d / 2, 0 ], geometry6 ],
				];

				for ( let i = 0; i < parameters.length; i ++ ) {

					p = parameters[ i ];
					line = new THREE.Line( p[ 3 ], p[ 0 ] );
					line.scale.x = line.scale.y = line.scale.z = p[ 1 ];
					line.position.x = p[ 2 ][ 0 ];
					line.position.y = p[ 2 ][ 1 ];
					line.position.z = p[ 2 ][ 2 ];
					scene.add( line );

				}

				//

				document.body.style.touchAction = 'none';
				document.body.addEventListener( 'pointermove', onPointerMove );

				//

				window.addEventListener( 'resize', onWindowResize );

			}

			function onWindowResize() {

				windowHalfX = window.innerWidth / 2;
				windowHalfY = window.innerHeight / 2;

				camera.aspect = window.innerWidth / window.innerHeight;
				camera.updateProjectionMatrix();

				renderer.setSize( window.innerWidth, window.innerHeight );

			}

			//

			function onPointerMove( event ) {

				if ( event.isPrimary === false ) return;

				mouseX = event.clientX - windowHalfX;
				mouseY = event.clientY - windowHalfY;

			}

			//

			function animate() {

				camera.position.x += ( mouseX - camera.position.x ) * 0.05;
				camera.position.y += ( - mouseY + 200 - camera.position.y ) * 0.05;

				camera.lookAt( scene.position );

				const time = Date.now() * 0.0005;

				for ( let i = 0; i < scene.children.length; i ++ ) {

					const object = scene.children[ i ];

					if ( object.isLine ) {

						object.rotation.y = time * ( i % 2 ? 1 : - 1 );

					}

				}

				renderer.render( scene, camera );

			}

		</script>
	</body>
</html>
